2017-01-13_REPORT - C1996083 ‎(3)‎

• Permit No: C1996083
• IBM Index Class Name: Report
• Doc Date: 1/13/2017
• Doc Name: Quarterly Waste Bank Inspection Report
• From: J.E. Stover & Associates, Inc
• To: DRMS
• Annual Report Year: 2016
• Report Quarter_Month: 4
• Permit Index Doc Type: Waste Pile/Fill Report
• Media Type: D
• Archive: No

CWDA No. 2
#01349-0001 Huddimon-Berry
01/12/17 ' mei ..-p LL,
Discussion of Inclinometer Monitoring
The latest inclinometer readings indicate no major movements since the last quarterly reading.
In general, the 4th Quarter 2016 monitoring data does not provide any indication of instability in
CWDA No. 2.
Vibrating Wire Piezometers
Between 2005 and 2012, a total of ten vibrating wire piezometers were installed in CWDA No.
2. However, several of the piezometers have been damaged or have otherwise ceased to
function. Currently, five of the piezometers are functional.
Monitoring of the functioning piezometers was completed by DOWL on December 14th, 2016.
The attached monitoring report prepared by DOWL includes the piezometer monitoring data and
the data is summarized in the following table.
VWP ID
Initial Pore
Pressure
(psi)
9/26/16 Pore
Pressure
(psi)
12/14/16 Pore Difference Since
Pressure Installation
(psi) (psi)
Difference
Since Last
Reading (psi)
VWP-05
6.8
2.3
2.0 -4.8
-0.3
VWP-06
11.3
14.0
13.6 +2.3
-0.4
VWP-08
8.2
9.9
9.9 +1.7
1 0.0
VWP-09
2.8
3.0
2.8 0.0
1 -0.2
VWP-10
-1.9
-1.7
-1.8 +0.1
1 -0.1
Discussion of Vibrating Wire Piezometers
i�><
VWP-05 was installed on August 3, 2005 near the toe of CWDA No. 2 adjacent to the access
road/bench. The pore pressures recorded at VWP-05 have shown some seasonal fluctuations;
however, the range of pore pressure changes is fairly small. In general, HBET does not believe
that the pore pressures in VWP-05 are cause for concern regarding stability of the gob pile.
VWP-06
VWP-06 was installed on June 5, 2009 near the existing top of CWDA No. 2. The pore
pressures recorded at VWP-06 have fluctuated since installation. In general, the fluctuations
have been seasonal and reflect the level of coal mine waste placement activity on top of CWDA
No. 2. Although an increase was recorded in the 1St Quarter 2016, the pore pressures recorded in
VWP-06 have decreased since then. In general, HBET does not believe that the measured pore
pressures are an indication of any instability in CWDA No. 2.
VWP-08
VWP-08 was installed on June 5, 2009 at a slightly lower elevation than VWP-06. The pore
pressures recorded at VWP-08 have fluctuated since installation. However, the fluctuations have
generally been within a narrow range of values. The measured pore pressures are generally
consistent with the level of coal mine waste placement activity at CWDA No. 2.
As indicated in the referenced Stability Evaluation report, the stability of CWDA No. 2 is
sensitive to increases in pore pressures in VWP-08. An increase in the pore pressure of 7 psi in
VWP-08 would result in a reduction of the Factor of Safety to below 1.5.
X:\2008 ALL PROJECTS\01349 -Bowie Resources, LLC\01349-0001 Bowie Mine\200 - Geo\Gob 2\ Instrumentation Monitoring\2016\01349-0001 GP2 4thQ 2016 L011117.doc 2